The economy all over the world today is built on the basis of fossil fuel, such as coal, oil and natural gas. However, all of these non-reproducible fossil energies are continuously exhausted. Since the beginning of the 21st century, the global energy problems and the consequent problems of environmental pollution and climate warming are becoming more and more prominent and gradually intensified. Because of the outstanding advantages of wide and broad distribution, a large scale resources, pollution-free, clean, safe, and easy to obtain, the solar energy is considered to be one of the most promising renewable energy.
To take full advantage of the energy of sunlight, new type of materials for absorbing sunlight are continually developed, among others, the inorganic semiconductor materials are more widely developed and applied, such as employed in silicon cell for the ground, however, due to the complicated manufacturing process, high cost, its application is limited. Thus new type of organic optoelectronic materials for substitution of nonorganic material is seeked to reduce the cost and expand the range of applications.
In recent years, more and more researches have been focused on the organic photovoltaic materials which are employed on the optoelectronic devices such as organic solar cells. The organic solar cell is a new type of solar cell, which converts the solar energy into electrical energy. Compared to the disadvantages of limited source, expensive price, toxic, complicated manufacturing process and high cost of the inorganic semiconductor material, the organic solar cell has the incomparable advantages that the inorganic solar cell doesn't have, such as wide sources of raw materials, a variety of structures and good regulatability, low cost, safety and environmental protection, simple manufacturing process, light weight, possibly to produce in a large flexibly area, and the like, can be widely used in construction, lighting and power generation and other areas, thus it has an important development and application prospects. Therefore, many domestic and foreign research institutions and enterprises are paying considerable attention and investment to the field of organic solar cell. However, until now, the photoelectric conversion efficiency of the organic solar cell is much lower than that of inorganic solar cell. Therefore, the development of new organic photovoltaic materials has much importance for improving the efficiency of organic solar cells and other semiconductor devices.